Older versions of VIOS servers do not send the firmware level in the VPD
buffer for the ibmvnic driver. Thus, not only the current message is mis-
leading but the firmware version in the ethtool will be NULL. Therefore,
this patch fixes the firmware string and its warning.

Fixes: 4e6759be ("ibmvnic: Feature implementation of VPD for the ibmvnic driver")
Signed-off-by: NDesnes A. Nunes do Rosario <desnesn@linux.vnet.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>